In response to demands for high-quality liquid crystal displays, technologies for improving the image quality of liquid crystal displays are being developed. A color liquid crystal display normally includes a liquid crystal display element, a color filter, and a backlight. The backlight illuminates the liquid crystal display element from behind, the liquid crystal display element controls transmission of light from the backlight, and the light that passes through the color filter is recognized by human eyes as an image.
A cold cathode fluorescent lamp (CCFL) tube has been widely used as the backlight. However, since the CCFL tube includes hazardous substances such as mercury and consumes a large amount of power, the CCFL tube is being gradually replaced with a light-emitting diode (LED) that is more environment-friendly. A light source using LEDs can be dynamically turned on and off and therefore makes it possible to reduce the power consumption and to improve the image quality and the reliability of a liquid crystal display. For these reasons, LEDs are currently used for liquid crystal displays of small devices such as cell phones and are also starting to be used for liquid crystal displays of larger devices.
FIG. 11 is a drawing illustrating a configuration of a related-art liquid crystal display including a CCFL tube. The liquid crystal display includes a liquid crystal display element 101 and a CCFL tube 102 used as a light source and disposed behind the liquid crystal display element 101. The liquid crystal display also includes a signal processing unit 103 for processing an input image signal and an image quality improving unit 104 for improving the image quality of the image signal. The liquid crystal display element 101 displays an image based on the image signal input from the image quality improving unit 104.
Patent document 1 discloses a method for adjusting image quality of a liquid crystal display.
[Patent document 1] Japanese Laid-Open Patent Publication No. 2008-134466